Medical devices of various types operate using an implanted component, and an external unit which is required to be linked to the implanted component, for example by an RF or inductive link, to provide the required functionality. The following discussion will be principally in the context of cochlear implants, but other similar issues arise for devices such as spinal, visual or other neural stimulators, and other medical implant applications.
In the case of cochlear implants, the system is generally configured as an external speech processor, and an implanted receiver/stimulator device. The internal device includes an electrode array-for providing electrical stimuli to the cochlea, electrical circuitry to generate the stimuli, and a means for receiving signals and power from the external speech processor. One arrangement, generally used in devices manufactured by the applicant, uses an inductive link to transfer power and data between the external speech processor unit and the implanted receiver/stimulator device. For the purposes of this invention however, the precise mechanism used is not presently relevant.
Conventionally cochlear implant devices have been arranged such that the implanted unit responds to commands from a compatible processor, but does not store patient specific data or identification codes in such a way so as to exclude the implanted unit responding to any processor unit. In conventional systems the patient specific data and programming is stored in the external speech processor and there is no data retained in the implant when it is powered down.
One issue with such devices is that in some situations, for example in a facility for the hearing impaired, it is possible for users to inadvertently swap speech processors. Each speech processor will contain a set of data specific to each individual—for example, speech processing strategies, stimulus coding strategies and electrode mapping parameters. If the wrong speech processor is used for a patient, then the use of the incorrect parameters will cause at best poor speech perception by the user, and at worst may cause pain and discomfort. Present cochlear implant systems do not incorporate mechanisms to prevent such a problem arising.
Similarly, if the speech processor is lost or damaged, the only record of the appropriate parameters for the patient is stored at the clinic which provided the programming for the processor. The clinician needs to then access the patients records and identify the implant serial number to initiate a programming session. If this is not readily available, then a new speech processor must be programmed from the beginning, which is a complex and time consuming process. Similar issues arise for other implanted devices which use an external component to provide ongoing data to an implant.
With this in mind, one object of the present invention is to provide an implanted device which allows for desired operation of the device through use of a compatible generic external component.
A further object of the present invention is a system which prevents inadvertent operation of an implanted medical device with incorrect parameters.
Yet a further object of the present invention is a system which allows for a simple process of exchanging external processors and accessing of patient specific data.